This invention relates to the field of connectors for printed circuit boards and similar applications, and more particularly, this invention relates to the transfer of high frequency, radio frequency signals between cooperating printed circuit boards.
Traditionally, high frequency radio frequency signals greater than about 500 MHz require subminiature coaxial connectors (SMA) that work in conjunction with connected coaxial cables for transferring signals between printed circuit boards or other components. Although these subminiature coaxial connectors are semi-precision, subminiature devices used with coaxial cables, including flexible and semi-rigid cabling, the types of connections required to make high frequency signal transfer adequate are relatively large and expensive.
Subminiature coaxial connectors operate at broadband frequencies and have low reflections. Many are designed to have a constant 50 Ohm impedance, making them advantageous for use in various applications in the microwave industry. Many different types of SMA connectors are available, but these connectors are large and expensive to use in some designs.
Some surface mount, pressure contact connectors have been designed for use in traditional DC signal connections, but usually never for transferring high frequency radio frequency signals (up to 4 GHz or more). Although some connectors have been used for transferring one of either DC signals or high frequency signals, such as disclosed in U.S. Pat. No. 5,188,534; 5,129,832; 5,595,490; and 5,991,165, adequate connection methods have not been known that allow the mixing of high frequency and DC signals on the same surface mount contact connector without impacting performance. It is also desirable if high frequency signals could be transferred with a solderless connection through a low cost, surface mount, spring or similar contact, while also allowing transfer of some DC signals. Additionally, many prior art connectors require solder connections at both ends, making assembly of the circuit boards and other component assemblies more difficult.
It is therefore an object of the present invention to provide a surface mount, pressure contact connector system that allows mixing of high frequency and DC signals without impacting performance.
It is another object of the present invention to provide a connector system between cooperating circuit boards that allows high frequency signals to be transferred with a solderless connection through a low cost, surface mount, spring or similar contact.
The present invention provides a connection method for connecting a pair of cooperating printed circuit boards and allowing high frequency, radio frequency signal transfer in a solderless connection to a second printed circuit board. It also permits DC signal transfer.
In accordance with the present invention, a housing member has a clip receiving slot and a circuit board engaging surface that is positioned against a first printed circuit board. At least one electrically conductive clip member that acts as a spring-like pin has opposing ends and is received within the clip receiving slot. One end of the clip member is readily secured by soldering to a circuit on the first printed circuit board. Another end of the clip member is biased into connection with a circuit of a second printed circuit board such that high frequency radio frequency signals are transferred from one printed circuit board to the other printed circuit board via the clip member.
In yet another aspect of the present invention, the connector system includes a plurality of housing members positioned adjacent to each other such that respective electrically conductive clip members are received within the housing members and positioned for interconnecting radio frequency signal lines, ground lines and DC signal lines that are formed on first and second printed circuit boards.
In yet another aspect of the present invention, the housing member is formed from plastic and is substantially rectangular configured. It includes a flat circuit board engaging surface that rests against the first circuit board. The electrically conductive clip member is substantially v-shaped and has a first leg member and an end that engages a circuit or trace on the first circuit board member. A second leg member includes an end that is spring biased against a circuit or trace on the second circuit board member. The end of the second leg member includes a bent contact forming a radius (concave) surface to aid in engaging a circuit on the second board member. The housing member includes a shoulder formed within each clip receiving slot that engages the second leg member to maintain a biasing force not only against the shoulder, but against the second circuit board to which it engages.
In yet another aspect of the present invention, a plurality of electrically conductive clip members that act as spring-like pins have opposing ends and are received within respective clip receiving slots. One end is readily secured by soldering to the circuit on the first printed circuit board and the other end is biased in connection with a circuit of a second printed circuit board. A clip member interconnects a radio frequency signal line and adjacent clip members interconnect ground lines and DC signal lines for transferring high frequency signals, ground connections and DC signals from one printed circuit board to the other printed circuit board via the clip members.
A method is also disclosed for connecting a pair of cooperating printed circuit boards and comprises the step of soldering to a circuit of a first printed circuit board an end of at least one electrically conductive clip member that is received within a clip receiving slot of a housing member having a circuit board engaging surface that rests against the first printed circuit board. The other end of the electrically conductive clip member is biased against the circuit of the second printed circuit board.